function isExternal(path) {
  return /^(https?:|mailto:|tel:)/.test(path);
}

function validUsername(str) {
  const valid_map = ['admin', 'editor'];
  return valid_map.indexOf(str.trim()) >= 0;
}

function validURL(url) {
  const reg =
    /^(https?|ftp):\/\/([a-zA-Z0-9.-]+(:[a-zA-Z0-9.&%$-]+)*@)*((25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]?)(\.(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])){3}|([a-zA-Z0-9-]+\.)*[a-zA-Z0-9-]+\.(com|edu|gov|int|mil|net|org|biz|arpa|info|name|pro|aero|coop|museum|[a-zA-Z]{2}))(:[0-9]+)*(\/($|[a-zA-Z0-9.,?'\\+&%$#=~_-]+))*$/;
  return reg.test(url);
}

function validLowerCase(str) {
  const reg = /^[a-z]+$/;
  return reg.test(str);
}

function validUpperCase(str) {
  const reg = /^[A-Z]+$/;
  return reg.test(str);
}

function validAlphabets(str) {
  const reg = /^[A-Za-z]+$/;
  return reg.test(str);
}

function validEmail(email) {
  const reg =
    /^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
  return reg.test(email);
}

function isString(str) {
  if (typeof str === 'string' || str instanceof String) {
    return true;
  }
  return false;
}

function isArray(arg) {
  if (typeof Array.isArray === 'undefined') {
    return Object.prototype.toString.call(arg) === '[object Array]';
  }
  return Array.isArray(arg);
}

export {
  isExternal,
  validUsername,
  validURL,
  validLowerCase,
  validUpperCase,
  validAlphabets,
  validEmail,
  isString,
  isArray,
}
